LOOSE BODY VERSUS TROCHLEAR BIOPSY MATRIX-INDUCED AUTOLOGOUS CHONDROCYTE IMPLANTATION (MACI) MOCART SCORES AND IKDC REPORTED OUTCOMES IN PEDIATRIC PATIENTS

BACKGROUND: Third generation autologous chondrocyte implantation (ACI) has traditionally used biopsies from non-weightbearing sites within the knee for culture and growth. Given the potential risk of functional deficits from this procedure, other donor sites are being investigated. A recent study showed no difference in the viability of the MACI implant using biopsies from the standard intercondylar region compared to biopsies from the osteochondral loose body. However, clinical outcomes using these two different donor sites remains unknown. The purpose of this study was to asses differences in clinical outcomes as measured by Magnetic Resonance Observation of Cartilage Repair Tissue (MOCART 2.0) and International Knee Documentation Committee (IKDC) scores at a minimum of 2 years post-implantation in patients who underwent a MACI procedure in the knee using cartilage grown from either the intercondylar notch or the osteochondral loose bodies. METHODS: A retrospective study was performed on all ACI procedures from 2014 to 2017 at a single institution. Patients were split into two groups: one group having their cartilage derived from a standard intercondylar biopsy while the other group had their cartilage derived from osteochondral loose bodies. At a minimum 1-year post-implantation, MRIs of the implantation site were performed and three individual orthopaedic surgeons used the MOCART 2.0 knee score to assess the cartilage. Interclass correlation coefficients (ICC) were calculated between the 2 groups. IKDC scores were determined at a minimum 2 years after implantation. Differences between outcomes were compared using a Wilcoxon rank-sum test. RESULTS: The intraclass coefficient between examiners for the MOCART scoring was excellent at 0.94. With regards to the MOCART score, the loose body group had a statistically insignificant 15-point lower median score at 65 (IQR 61-83) compared to the intercondylar group at 80 (IQR 60-89) (p=0.46). With regards to the IKDC, the loose body group had a statistically insignificant 1-point higher median score at 85 (IQR 69-96) compared to the intercondylar group at 84 (IQR 53-99) (p=0.79). CONCLUSIONS: This study demonstrates no difference in MOCART and patient reported outcomes in patients who had MACI from cartilage derived from either a standard intercondylar biopsy or an osteochondral loose body. Surgeons should be aware that using cartilage derived from osteochondral loose bodies is a viable option for MACI as it eliminates donor site morbidity and has comparable MOCART and functional outcomes at 2 years post-implantation compared to the standard intercondylar biopsy. LEVEL OF EVIDENCE: Level III